Process for treating coal



jo N7@ E. F. NELSON PROCESS FOR TREAT'ING COAL Filed Jan. 25, l968United States Patent O 3,488,278 PROCESS FOR TREATING COAL Edwin F.Nelson, Arlington Heights, Ill., assignor to Universal Oil ProductsCompany, Des Plaines, Ill., a corporation of Delaware Filed Jan. 25,1968, Ser. No. 700,535 Int. Cl. Cg 1/08, 1/04 U.S. Cl. 208-10 8 ClaimsABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This inventionrelates to a coal treating process. It also relates to a process forliquefying coal using a selective solvent. It particularly relates to aprocess for obtaining valuable liquid hydrocarbons from solidparticulate coal utilizing counter-current solvent extraction and,preferably, simultaneous hydrogenation within the extraction zone.

It has long been known that hydrocarbon gases, liquids, pitch andchemicals may be obtained in some form from coal which is mined from theearth. Usually, the prior art has employed destructive distillation orother gasification processes for the conversion of coal into these morevaluable and useful products. Recently, the prior art has developed ahigh pressure hydrogenation of coal technique to effectuate suchconversion. Still more recently, methods involving solvent extractiontechniques have been developed for obtaining useful fuels and chemicalsfrom coal whereby the coal is contacted with a selective solvent whichacts as a hydrogen donor for supplying sufficient hydrogen to the coalto aid in converting it into a liquid state.

Following the solvent extraction step, the prior art schemes haveutilized various recovery procedures, such as hydrogenation of theliquid coal extract, for increasing its value and utility together withretorting or coking of the residual materials obtained from the solventextraction step to still further convert these coal derived productsinto more valuable products. However, none of the aforementioned priorart procedures have been commercially efficient or feasible to warrantwidespread cornmercial exploitation of converting coal into liquidproducts. Generally, the deficiencies in the prior art schemes have notonly involved capital investment problems, and disposal problems of theresidue or waste frequently having high metals content, but alsoinvolved liquid product quantity and quality problems which have yet tobe solved in an economical and facile manner.

Since it is clear to those skilled in the art that the vast mineralreserves of butuminous coal represent an extremely important supply ofenergy, it would be desirable to improve upon the prior art techniques,particularly the solvent extraction technique in order to reduce thecost of obtaining high quality petroleum-type products from coal.Accordingly, the present invention provides an improved process for theconversion of solid coal into liquefied products utilizing an improvedsolvent extraction technique.

3,488,278 Patented Jan. 6, 1970 SUMMARY OF THE INVENTION Therefore, itis an object of this invention to provide a process for treating coal.

It is also an object to provide a process for the liquefaction of coalwhereby valuable liquid hydrocarbons are obtained therefrom.

It is a specific object of this invention to provide an improved processfor treating coal which involves the counter-current extraction of solidparticulate coal with a selective solvent.

It is another specific object of this invention to provide an improvedmethod for the liquefaction of particulate coal by a counter-currentsolvent extraction in a. facile and economical manner.

Thus, in accordance with the practice of the present invention, there isprovided a process for treating coal which comprises passing crushedcoal into the upper end of a vertically disposed liquefying zonemaintained under coal liquefying conditions, introducing coal solventinto said zone at a plurality of spaced points from the lower end ofsaid zone, removing from the upper end of said zone rich solventcontaining dissolved coal, and withdrawing from the lower end of saidzone a residue stream containing ash and undissolved material.

Another embodiment of this invention provides a process comprisingcontacting crushed coal in a contacting zone with solvent in continuouscounter-current fashion, said coal being introduced into said zone atthe upper end thereof and said solvent being introduced at a pluralityof spaced points from the lower end thereof, under conditions sufficientto dissolve more than 50% M.A.F. coal into said solvent and thereafterseparating the solvent containing dissolved coal from the ash andundissolved material.

It can be seen from the description of the invention presented thus farthat the essence of the present invention embodies the use ofcounter-current solvent extraction whereby the lean solvent isintroduced into the lower end of the extraction zone at a plurality(e.g. from 2 to 5) of spaced points within the zone. It is believed thatthe introduction of the lean solvent in this unique fashion results inimproved contact between the solvent and the coal while providing acontinuous manner of converting solid coal into liquefied products in amore facile and economical manner.

In brief, the operation of the present invention involves maintainingthe coal liquefier or extraction zone under conditions of elevatedtemperature and pressure sufiicient to maintain the lean solvent insubstantially liquid phase through the extraction zone while providingthe necessary dissolving conditions to transform the solid coal intoliquefied products. A suitable residence time is maintained in theextraction Zone by utilizing the technique of hindered settling wherebythe upflow velocity of the liquid solvent provides hindrance to thegravity pull of the solid coal particles down the zone. By introducingthe solvent into a plurality of points within the zone, the hinderedsettling technique can be advantageously exploited by providing varyingdegrees of solvent purity and solvent velocity throughout the extractionzone.

Additionally, as will become evident from the description presentedhereinbelow, the efficiency of the coal treating process can beincreased by the introduction of hydrogen or a hydrogen-containing gasinto the extraction zone, preferably, at a lower end thereof. The use ofthe hydrogen-containing gas can be further enhanced by introducing intothe extraction zone'a suitable solid hydrogenation catalyst which,preferably, would be introduced into the upper end of the solventextraction zone.

It is believed that one of the reasons the practice of the preferredembodiment of the invention produces such desirable results is themanner in which hydrogen balance is maintained in the system. Forexample, during the extraction operation it is also believed thathydrogen is transferred from the solvent to the coal thereby aiding inthe conversion of the coal into a liquid product. Thus, the solvent, ineffect, becomes reduced in hydrogen content. Preferably, therefore,hydrogen gas is introduced into the extraction zone in order to restorethe hydrogen content of the solvent to substantially its originalhydrogen content. In other words, in the broad embodiment of theinvention, as the solvent passes upwardly through the solvent extractionzone, it becomes more and more depleted in hydrogen content as itcontacts the crushed coal passing downwardly through the zone. Whileunique advantages were found in this manner of operation over the priorart schemes, it was also discovered that the inventive method could befurther improved by having the extraction take place in the presence ofa hydrogen gas in such a manner that the solvent substantiallythroughout the extraction zone is maintained, in effect, in its highesthydrogen content thereby significantly increasing the efficiency of thecoal conversion reaction.

By operating in this preferred manner and in some cases utilizinghydrogenation catalyst in the extraction zone, one of the ultimatelyrecovered hydrocarbon products is now eminently suitable for recycle tothe pulverization zone since its hydrogen content has been restored to ahigh level.

The coal preferred for use in the practice of the present inventiveprocess is of the bituminous type, such as Pittsburgh Seam Coal. Morepreferably, however, the bituminous coal is a high volatile content coalhaving a solids content greater than about 20 weight percent of M.A.F.coal (moisture and ash-free coal). Although the inventive method will bedescribed with reference to the treating of bituminous coal, it iswithin the concept of the present invention to apply the inventiveprocess to a sub-bituminous coal, lignite, and other solid carbonaceousmaterials of natural origin.

Apparatus for use in pulverizing coarse coal to prepare feed to thepresent process may be of any type known to those skilled in the art.Conventional ball mills or rod mills may be used with satisfactoryresults. Preferably, the apparatus must be able to pulverize lump orcoarse coal in the presence of significant quantities of liquids, suchas the coal solvent, without difiiculty. Those skilled in the art arefamiliar with the kinds of apparatus for processing wet solids and thecrushing yand grinding thereof so that no detailed discussion of theapparatus need be presented herein. The primary requirement for crushingand grinding of the lump coal is that coarse coal usually having anaverage particle diameter in excess of 0.08 inch and, typically, 0.25 to2.0 inches must be processed therein and reduced in size to an averageparticle diameter which would be of at least a -8 Tyler screen size and,preferably, would be reduced to an average particle size of -14 Tylerscreen size. As used herein, the term Tyler screen refers in allinstances to the commercial Tyler standard screens. A correlationbetween Tyler screen mesh and average particle diameter is as follows:

Tyler screen Average diameter of The coal feed utilized in the presentinvention may be introduced into the solvent extraction zone in itssubstantially dry state through lock hopper means, screw conveyor means,or other means available to those skilled in the art. In some cases,however, it may be advantageous to introduce the coal into theextraction zone as a slurry, i.e., a mixture of coal and solvent. Theslurry method may advantageously be used if the solvent has been presentduring the crushing and grinding operation of the coarse coal. In manycases, it is advantageous to have the solvent present during thecrushing and grinding operation.

With respect to the benefit gained from having the solvent presentduring the pulverization step, it is believed that at the point of shearfor the crushing and grinding of the coal, the shear site is extremelyreactive and hydrogen, therefore, can be transferred into that site moreeasily than if the coal is pulverized prior to contact with the solvent.In addition, the smaller particles of coal whichare sheared away from arelatively large lump irnmediately exposes not only the highly reactiveshear site to the solvent, but also exposes an extremely large surfacearea to the solvent, thereby enabling the resulting small particles ofcoal to almost immediately dissolve in the solvent and become a part ofthe liquid coal extract.

Additionally, there has been some discussion in the prior art that thepresence of oxygen or oxygen compounds on the surface of the coal makesit diflicult for the coal to react properly with the suitable solventsfor the conversion thereof into liquid coal extract. It is furtherbelieved therefore, that by pulverizing or by crushing the coal in thepresence -of :a liquid solvent, oxygen compounds or the presence ofoxygen have been excluded from the highly reactive shear sites along thecoal, thereby further enabling the transfer of the hydrogen from thesolvent to the coal to become of significantly increased efficiency.

Extraction of coal by means of a selective solvent is, by definition, apartial conversion of the coal since not only is the coal reacted withthe hydrogen which is transferred from the solvent, but is, in thepreferred embodiment, also reacted with the hydrogen which is addedduring the extraction operation. In addition, there is a solutionphenomenon which actually dissolves the coal which has accepted thehydrogen into the solvent. Therefore, as used herein, the terms liquidcoal extract and liquefied coal fraction or dissolved coal or otherwords of similar import are intended to include the liquid product whichis obtained by treating the coal with a selective solvent and,generally, will be described on the basis of being solvent-free eventhough a portion of the liquid coal extract comprises hydrocarbonssuitable for use as the selective solvent.

The practice of the present invention is preferably performed underconditions which increase the kinetics of the reaction while maintainingthe components therein (except hydrogen) primarily or substantially inliquid phase; although, in some cases it may be desirable to practicethis invention in the presence of a vaporized solvent by using avapor-iiuid extraction technique.

Suitable solvents for use in the practice of this invention are thosewhich are of the hydrogen-donor type and are at least partiallyhydrogenated and include naphthalenic hydrocarbons. Preferably, thesolvent is one which is in liquid phase at the recommended temperatureand pressure for the extraction and/or pulverization step. Mixtures ofhydrocarbons are generally employed and preferablly are derived fromintermediate or final products obtained from subsequent processingfollowing the practice of this invention. Typically, these solventhydrocarbons or mixtures of hydrocarbons boil between about 260 C. and425 C. Examples of suitable solvents are tetrahydronaphthalene(Tetralin), Decaln, biphenyl,

methylnaphthalene, dimethylnaphthalene, etc. Other types of solventswhich may -be added to the preferred solvents of this invention forspecial reasons include phenolic compounds such as phenols, cresols, andxylenols. It is also to be recognized that in some cases it may bedesirable during a subsequent separation step prior to the removal ofthe solvent from the liquid coal extract to add an anti-solvent, such assaturated paraffinic hydrocarbon like hexane, to aid in theprecipitation of tarry and solid residue from the coal extract of theinvention.

However, in the selection of a suitable solvent it must be recognizedthat the solvent must have the ability to transfer hydrogen to thepulverized coal during the extraction step. In other words, it is arequirement of the broad embodiment of this invention (Le. no addedhydrogen) that the rich solvent leavingthe extraction zone having coaldissolved therein has a reduced hydrogen content compared to thehydrogen content of the lean solvent which is added to the extractionzone. It has also been explained that another critical feature of thepreferred embodiment of this invention is the selective hydrogenation ofthe solvent during extraction in order to increase its hydrogen contentso that hydrogen may be more easily transferred from the solvent to thecoal.

`One of the convenient ways of optimizing the specific hydrotreatingoperation during extraction is to use the I-factor analysis fordetermining the degree to which hydrogen has been added to the solvent.This analytical technique permits the characterization of various typesof aromatics in a hydrocarbon mixture by means of the I-factor analysis.The technique utilizes mass spectrometer analysis employing a lowionizing voltage. The ionizing voltage is chosen such that only thosehydrocarbons to be characterized are ionized while other hydrocarbontypes are not ionized under the potential chosen. For example, sincecompounds more saturated than aromatic hydrocarbons, such as theparaffin hydrocarbons, have an ionization level above v volts theionization chamber is thus maintained at a potential of about 7 volts sothat only the aromatic hydrocarbons are ionized and the saturatedcompounds will not be observed on the mass spectrum. As those skilled inthe analytical art know, the mass spectrum reveals molecular ion peakswhich correspond to the molecular weight of the aromatic compound. Thus,the technique permits characterization of the aromatic hydrocarbons 'bymeans of the general formula CnH2n J where I is the herein referred toI- factor for the practice of the present invention. The following tableshows the relationship between the J -factor and the type of aromatic.

Type of aromatic hydrocarbon I-factor number Alkyl benzenes and benzene6 Indanes, Tetralins 8 Indenes 10 Alkyl naphthalenes and naphthalene 12Acenaphthenes, tetrahydroanthracene 14 Acenaphthalenes,dihydroanthracenes 16 Anthracenes, phenanthrenes 18 Using this J-factoranalysis in characterizing the degree of hydrogenation during extractionallows for the optimum treatment of said solvent to produce a highquality hydrogen enriched solvent for use in converting coal into liquidcoal extract. The I -factor analysis is simply a convenient means foroptimizing the hydrogenation technique in the practice of the preferredembodiment of the present invention.

The operating conditions maintained in the extraction zone may be Variedwidely. The temperature, for example, may be varied essentially fromatmospheric temperat'ure to a relatively high temperature. It isdistinctly preferred in the practice of this invention that thetemperature of the coal and the solvent be maintained at a relativelyhigh level, say, from 300 C. to 500 C. The pressure in similar mannermay be varied over an extremely wide range; for example, fromatmospheric pressure, to, say, 10,000 p.s.i.g. with a preferred pressurebeing about 500 p.s.i.g. In all cases it is distinctly preferred thatthe operating conditions be chosen so as to maintain the solvent anddissolved coal in substantially liquid phase. These conditions shouldalso be chosen so as to maintain the extraction zone substantiallyliquid-full; at least in liquid phase over the volume of the extractionzone where the major portion of the dissolving action takes place.

The amount of solvent which is used in the present invention should befrom 0.2 to 10 pounds of solvent per pound of solid coal entering theextraction zone. As previously mentioned, it may be desirable to use theslurry technique for feeding the coal into the extraction zone. In suchcase, if solvent is used as the carrying medium in the slurry, then, ofcourse, solvent lwould enter the extraction zone along with the solidcoal feed. It is to be noted that in the slurry technique of feedingcoal to the extraction zone there has already been at least partialliquefaction of the coal at that point. 'Satisfactory results may beobtained in the extraction zone in utilizing approximately equal amountsof solvent to coal on a weight basis. The amount of solvent entering theplurality of spaced points (excluding the coal feed point in the case ofslurry feed) may be varied in any .manner desired by those skilled inthe art. It is preferred, however, that from 50% to 90% by volume of thetotal lean solvent entering the extraction zone be introduced throughthe uppermost point. Therefore, for example, if three introductionpoints are used the amount of solvent may be varied as :15 :5, 60:30:10,70:15:15, 70:20:10, etc. In the preferred embodiment of his invention,three introduction points are used and the amount of solvent introducedshould be in the 70:20:10 ratio. The 10% amount of solvent which entersthe lowermost introduction point passes into the extraction zone and inmost cases ows in essentially a downward fashion thereby washing thelower end of the extraction zone free of ash and residue.

As used herein, the term spaced or words of similar import is intendedto include spaced arrangements whereby the inlet points are in astraight line, i.e. one totally above the other; or in an upwardlystaggered arrangement, or in an upwardly spiral arrangement equallyspaced around the extraction shell; or in any other arrangement desired`by those skilled in the art as long as the plurality of inlet pointsare arranged in a vertically disposed direction. It is also distinctlypreferred that the spaced points be concentrated in the lower end of theextraction zone, ie., below the said point of a vertically disposedextraction column.

As previously mentioned, the upwardly flowing solvent in the extractionzone and, preferably, the upwardly owing hydrogen gas provide aresidence time for the solid coal to be in contact with the solventthrough the hindered settling technique. Generally, a residence timefrom 30 seconds to 5 hours is sufficient and, preferably, the amount ofhydrogen gas introduced into the system is sucient to dissolve the coaland to substantially maintain the hydrogen content of the solvent atsubstantially the level of the lean solvent. In all cases, thecombination of operating conditions should be suicient so that a totalin excess of 50% by weight and, typically, from 70 to by weight of theM.A.F. coal has been liquefied. The amount of hydrogen gas necessary toperform this pressured function may range from 1,000 to 100,000 standardcubic feet per barrel of lean solvent entering the system. Typically,however, the amount of hydrogen added to the extraction zone in thepreferred embodiment will be in the range from 2,000 to 10,000 standardcubic feet per barrel. However, the amount of hydrogen entering theextraction zone should not be in excess of that which would causefoaming or carryover of solid coal out of the upper end of theextraction zone. Those skilled in the art are familiar with theteachings presented herein and general knowledge will understand how tocontrol the amount of hydrogen in conformity with the J-factor analysison the solvent leaving the extraction zone and on other designparameters.

While the purpose of the extraction zone, including the preferredembodiment of adding hydrogen to the extraction zone, is tosubstantially complete the conversion of the coal into a liquid coalextract, it may also be desirable to add to the extraction zone ahydrogenation catalyst. The catalyst used may be conventional, may behomogenous `or heterogenous and may be introduced in the pulverizationzone and/or extraction zone in admixture with the liquid solvent or withthe solid coal or may be introduced as a separate stream into the upperend of the extraction zone. Those skilled in the art, from a knowledgeof the characteristics of the coal, solvent and the properties desiredfor the end product will know whether or not it may be desirable to useany or all of these desirable features in the extraction zone.Conventional solid, particulate hydrogenation catalyst (e.g. finelydivided) may be desirable, such as palladium on an alumina support or acobalt-molybdate catalyst or any other hydrogenation catalyst known tothose skilled in the art and applicable to the solvent-coal systemenvironment maintained in the extraction zone including the use of aslurry-catalyst system.

Hydrogenation in the extraction zone generally accomplished thefollowing functions: transfer of hydrogen directly to coal molecules;transfer of hydrogen to hydrogen donor molecules; transfer of hydrogenfrom hydrogen donor molecules to coal molecules; and combinations of theabove. Homogenous catalysts may be introduced with the coal, or hydrogendonor compounds, in the pulverization step prior to the extraction zone.Examples of catalysts suitable include compounds containing tin, nickel,molybdenum, tungsten, and cobalt.

Following the solvent extraction zone the solvent containing dissolvedoil is passed into a separation zone for the recovery therefrom ofvaluable hydrocarbon products. Typically, these products are normalgasoline boiling range products and/or chemicals, aromatichydrocarboncontaining fractions, heavy fuel oil fractions, and the like,the utility of which is well known to those skilled -in the art. Aspreviously mentioned, at least a portion of the coal extract is suitablefor use as a coal solvent and may, therefore, be recycled at least inpart to the solvent extraction zone as lean solvent therein.

The invention may be more fully understood with reference to theappended drawing which is a schematic representation of apparatus forpracticing the preferred embodiment of the invention.

DESCRIPTION DRAWING Referring now to the drawing, crushed coal having anaverage particle diameter of at least 8 Tyler screen size is introducedfrom hopper 10 into coal liqueiier 11 which is maintained under coalliquefying conditions. Lean solvent is introduced into the system vialine 12 and is split into spaced introduction points via lines 13, 14,and 15 in an amount suflicient to provide an upward flowing velocitywhich hinders the settling of the coal particles passing downwardlythrough liqueer 11. The amount of lean solvent entering the spacedintroduction points is in a ratio of 80:15:5, respectively, by volume.

Suicient hydrogen gas is introduced into l-iqueer 11 via line 19 andpasses in an upwardly flowing direction through the extraction zone. Atypical cobalt-molybdate hydrogenation catalyst in solid particulateform -is introduced into the upper end of liqueiier 11 via line 19.Thus, the lean solvent and hydrogen pass in counter-current fashion withthe coal and catalyst particles.

Rich solvent containing dissolved coal together with other gasesincluding hydrogen is removed from liqueer 11 via line 16 and passedinto recovery facilities. Conventionally, the hydrogen gas may beseparated (by means not shown) from the other materials and recycled toliqueiier 11. Similarly, a portion of the liquid coal extract may alsobe recovered (by means not shown) and returned to liqueer 11 as leansolvent therein. Ash and residue including solid catalyst is removedfrom the system via line 17 and passed into recovery facilities notshown for the reclaiming of the catalyst and reuse in the extractionzone.

In a manner of operating, the materials in contact at point 23 include.solvent which is relatively lean having been introduced via line 13,hydrogen gas, downward passing coal particles and catalyst particles. Inmany respects the condition of the materials at point 23 may be termedsemiplastic. As the material passes further down the column, thecondition at point 22 may be termed a condition of relatively high ashcontent zone since at that point substantially all of the coal to beextracted has been converted into liquid phase. In addition, thevelocity of the materials owing upwardly at point 23 is greater than theupward flow velocity of materials at point 22. One of the reasons forcontrolling the conditions in this manner of relative velocity is thatat point 23 there are significantly greater numbers of relatively tinecoal particles than at point 22.

By similar analogy, the condition at point 21 is one of extremely highash content with essentially no coal particles to be dissolved. Theintroduction of the hydrogen into the zone at point 21 creates acondition of relatively high turbulence which aids in the furtherseparation of any remaining coal particles from the undissolved ash,catalyst, and residue which continue down the column. Point 20 defines asettling zone where low Reynolds number liquid iiows are maintained sothat the ash, residue, and catalyst will have a chance to settle out ofthe liquid phase and be washed by at least a portion of the lean solventwhich enters liqueer 11 vial line 15 and passes downward as a washthrough the settling zone.

It was discovered in the practice of the present invention that theutilization of hydrogen gas in the coal liquetier permitted the use ofless solvent than would otherwise be required. Even though substantialbenefits over the prior art may be obtained through the use of theplurality of inlet points for the lean solvent, without the use ofeither hydrogen or a catalyst, the benefits to be obtained through thehydrogenation technique permit significant economies to be obtained overthe prior art scheme.

PREFERRED EMBODIMENT From the discussion presented hereinabove, thepreferred embodiment of the present invention includes a process forliquefying solid particulate coal which comprises introducing crushedcoal having an average particle diameter of at least -8 Tyler screeninto the upper end of a vertically disposed liquefying zone maintainedunder coal liquefying conditions, introducing solid particulate coal,hydrogenation catalyst into the upper end of said zone; passing coalsolvent into said first zone at from 2 to 5 spaced points from theirlower end of said zone; introducing hydrogen into the lower end of saidzone; removing from the upper end of said zone rich solvent containingdissolved coal; and withdrawing from the lower end of said zone a slurrycomprising solvent, ash, and said catalyst.

In a distinctly preferred embodiment of the present invention there isprovided the preferred process hereinabove wherein said conditions aresufficient to maintain said solvent substantially in liquid phase.

The invention claimed:

1. Process for treating coal which comprises passing crushed coal intothe upper end of a vertically disposed liquefying zone maintained undercoal liquefying conditions, introducing hydrogen-donor type coal solventinto said zone at a plurality of vertically spaced points in the lowerend portion of said zone, passing said crushed coal downwardly throughsaid zone in a state of hindered settling, removing from the upper endof said zone rich solvent containing dissolved coal, and withdrawingfrom the lower end of said zone a residue stream containing ash andundissolved material.

2. A process according to claim 1 wherein said coal liquefyingconditions include the presence of hydrogenation catalyst and hydrogen.

3. Process according to claim 1 wherein said plurality of solventintroduction points comprises from 2 to 3 points.

4. Process comprising contacting crushed coal in a contacting zone withhydrogen-donor type solvent in continuous countercurrent fashion, saidcoal being introduced into said zone at the upper end thereof and saidsolvent being introduced at a plurality of vertically spaced points inthe lower end portion thereof, passing said crushed coal downwardlythrough said zone in a state of hindered settling, under conditionssuiicient t dissolve more than 50% M.A.F. coal into said solvent, andthereafter separating the solvent containing dissolved coal from the ashand undissolved material.

5. Process according to claim 4 wherein said plurality of spaced pointscomprises from 2 to 3 points and said conditions include the presence ofhydrogen gas.

6. Process for liquefying solid particulate coal which comprisesintroducing crushed coal having an average particle diameter of at least-8 Tyler screen into the upper end of a vertically disposed liquefyingzone maintained under coal liquefying conditions, introducing solidparticulate coal hydrogenation catalyst into the upper end of said zone,passing hydrogen-donor type coal solvent into said zone at from 2 to 5vertically spaced points in the lower end portion of said zone, removingfrom the upper end of said Zone rich solvent containing dissolved coal,passing said crushed coal downwardly through said zone in a state ofhindered settling, and withdrawing from the lower end of said zone aslurry comprising solvent, ash and said catalyst.

7. Process according to claim 6 wherein said conditions are sufficientto maintain said solvent substantially in liquid phase.

8. Process according to claim 7 wherein said coal solvent is passedthrough in spaced points in a manner such that from t0 90% by volume ispassed through the uppermost point.

References Cited UNITED STATES PATENTS Re. 25,770 4/1965 Johanson 208-102,707,163 4/1955 Thibaut 208-10 3,184,401 5/1965 GOrIl 208-8 DELBERT E.GANTZ, Primary Examiner V. OKEEFE, Assistant Examiner

